This summer I am taking a geology class at Stanford, and last week we were talking about the Sierra Nevada’s exfoliated granite domes. On the hour-long drive home, the class discussion got me thinking about my first extended backpack years ago in the Mineral King backcountry with my brother Jim. We were woefully unprepared: although it was late in the season, our only shelter was a flimsy plastic tube tent, and our food consisted of packets of tasteless, freeze-dried glop.

Rachel Carson died on this day in 1964. Although she was already a well-known writer prior to Silent Spring, she is best remembered for this book that made the case against the indiscriminate spraying of pesticides such as DDT. In clear lyrical prose, her work focused attention on the danger these chemicals posed to wildlife as well as the risk of cancer and other health problems in humans. Carson herself died from complications from breast cancer. She was 56.